Hand 7 addressed boxes a year from Christmas (6)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

MR (form of address used to a 7d GENTLEMAN), containing (boxing) A (from clue text) + [y] ULE (Christmas) without the Y (abbreviation for year). Slang for a hand, though Chambers (or at least the edition I have) only recognises the word in the plural.